As input for our work we use static potentials computed with lattice QCD in the context of string breaking in Ref. [1]}. The basic principle to compute such potentials is to define suitable creation operators for a quark-antiquark pair and a meson-meson pair, e.g.
\(& & \hspace{-19.91684pt} \mathcal {O}_{Q\bar{Q}} = (\Gamma _Q)_{AB} \left(\bar{Q}_{A}(\mathbf {0})\;U(\mathbf {0}; \mathbf {r})\;Q_B(\mathbf {r})\right) \\& & \hspace{-19.91684pt} \mathcal {O}_{M\bar{M}} = (\Gamma _Q)_{AB}(\Gamma _q)_{CD} \left(\bar{Q}_{A}(\mathbf {0})\;u_D (\mathbf {0})\;\bar{u}_C(\mathbf {r})\; Q_B(\mathbf {r})\right) + (u \rightarrow d) ,\) 
